A series of firings of a liquid oxygen and gaseous hydrogen rocket injector assembly demonstrated the ability to design, to manufacture and to test a highly critical rocket engine component using selective laser melting manufacturing technology. Aerojet Rocketdyne designed and fabricated the injector by a method that employs high-powered laser beams to melt and fuse fine metallic powders into three dimensional structures.

Liquid oxygen/gaseous hydrogen rocket injector assembly. Liquid oxygen/gaseous hydrogen rocket injector assembly built using additive manufacturing technology is hot-fire tested at NASA Glenn Research Center’s Rocket Combustion Laboratory in Cleveland, Ohio. Credit: NASA. Click to enlarge.

Hot fire testing the injector as part of a rocket engine is a significant accomplishment in maturing additive manufacturing for use in rocket engines. These successful tests let us know that we are ready to move on to demonstrate the feasibility of developing full-size, additively manufactured parts.

—Carol Tolbert, manager of the Manufacturing Innovation Project at Glenn

This type of rocket engine injector—a complex machined piece—manufactured with traditional processes would take more than a year to make; with these new processes it can be produced in less than four months, with a 70% reduction in cost. The injector is one of the most expensive components of an engine, said Tyler Hickman, who led the testing at Glenn.

Aerojet Rocketdyne’s additive manufacturing program manager, Jeff Haynes, said the injector represents a significant advancement in application of additive manufacturing, most often used to make simple brackets and other less critical hardware.

The injector is the heart of a rocket engine and represents a large portion of the resulting cost of these systems. Today, we have the results of a fully additive manufactured rocket injector with a demonstration in a relevant environment.

—Jeff Haynes

Glenn and Aerojet Rocketdyne partnered on the project with the Air Force Research Laboratory at Edwards Air Force Base, Calif. At the Air Force lab, a unique high-pressure facility provided pre-test data early in the program to give insight into the spray patterns of additively manufactured injector elements.

The Manufacturing Innovation Project is supported by the Game Changing Technology Program in NASA’s Space Technology Mission Directorate, which is innovating, developing, testing and flying hardware for use in NASA’s future missions.